1. Field
The exemplary embodiments generally relate to transport apparatus and, more particularly, to robotic transport apparatus.
2. Brief Description of Related Developments
Generally transport apparatus employ end effectors or substrate holders that utilize passive contact (e.g. passive grip) between the substrate and the end effector. The maximum acceleration thresholds achieved with the passive grip end effectors may be heavily dependent on the choice of material used for passively contacting the substrate. Higher acceleration thresholds can be achieved with “rubber-like” materials such as Kalrez 4079, which is naturally more compliant than other materials such as alumina or quartz. On the other hand, the rubber-like materials tend to have higher adhesion forces which may be detrimental to substrate placement accuracy as well as process cleanliness. It is also noted that the rubber-like materials may not be capable of handling hot substrate. Materials like alumina and quartz are able to operate at higher temperatures and have lower adhesion forces than the rubber-like materials, however their acceleration thresholds (or friction coefficients) are reduced when compared to the rubber-like materials.
It would be advantageous to have a transport with a passive grip end effector that allows for maximized acceleration thresholds while maintaining at least low adhesion forces.
It is noted that the scale of the features illustrated in the drawings is for illustrative purposes only and is not representative of the actual scale of the features.